tree f05101f282d7dd368707f57e3bf3539ecbe0f064
parent 9f30ce3b82acb1f9582e49e9d87ab0d58c8f9ce4
author ztenghui <ztenghui@google.com> 1410379700 -0700
committer ztenghui <ztenghui@google.com> 1410393959 -0700

Re-triangulate the spot shadow.

Fix the valid umbra detection.

This looks better b/c every vertex will have one ray shooting at it, such that
we don't miss the corner.

This performs better too, due to the polygon intersection is removed and less ray
intersection. 2x performance for rect and circle for spot shadow in test app.

    b/17288227
    b/15598793
    b/16712006

Change-Id: I4a5ee397b9e192e93c8e35e6260b499e3e38a6f4